Perhaps you should try some spelling variations:
thien van » thi van
thu sach » tu sach, thuat sach, thuoc sach
dan tinh » doan tinh, dang tinh, dan trinh
thuc dan » thuc hanh, hoc dan, thuc vat
cau thuc » cau truc, cuu thuc, can thuc
hieu va » lieu va, hieu qua
tinh di » tinh doi, trinh di, tinh da
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
di cua » dai cua, doi cua, de cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach y ((sang ma) or (nang ma)) hoa. ((thien van) or (hieu va)) cau thuc dan tinh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((sang ma) OR (nang ma)) hoa. ((thien van) OR (hieu va)) cau thuc dan tinh di cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach y ((sang ma) or (nang ma)) hoa. ((thien van) or (hieu va)) cau thuc dan tinh di cua tre*.